Hydraulic pressure compensating means for internal combustion engine systems



Feb. 1, 1966 J. F. GILBERT 3,232,132

HYDRAULIC PRESSURE COMPENSATING MEANS FOR INTERNAL COMBUSTION ENGINE SYSTEMS Filed Aug. 15, 1963 RESERVOIR FIG./

INVENTOR JOHN E GILBERT W cm ATTORNEYS United States Patent 3,232,182 HYDRAULIC PRESSURE CGMPENSATENG MEANS FOR INTERNAL COMBUSTION ENGINE SYSTEMS John F. Gilbert, 309 Broadway, Hazard, Ky. Fiicd Aug. 15, 1963, Ser. No. 302,319 3 Claims. (CI. 92-43) This invention relates to hydraulic pressure responsive devices, and more particuladly to mechanisms for controlling the supply of hydraulic fluid provided by a pump system driven by a prime mover such as an internal combustion engine for actuating various load devices associated with an automobile driven by the engine.

One of the difficulties which has been encountered in the past in the operation of hydraulic servo-assisted power steering mechanisms provided on many automobiles, trucks and buses is that these devices require excessive amounts of power to be supplied by the hydraulic pumping mechanism under certain conditions, such as when the vehicles wheels are sharply turned when the vehicle is at rest.

When the vehicle is standing, the internal combustion engine is usually operating at idling speed, under which condition it is capable of delivering only the minimum amount of power to the hydraulic system. As a result, the sudden demand on the hydraulic supply system for turning the wheels quite frequently results inputting a sufficient load on the engine to cause it to stall.

One solution for this problem is to adjust the idling speed of the internal combustion engine to such a rate that an overload of this type will not cause it to stall. However, this arrangement is disadvantageous because the engine will thus use more fuel than necessary for it to maintain its normal idling speed.

Furthermore, if an automatic transmission for driving the vehicle is associated with the engine, the idling speed thus required to maintain a sufiicient reserve of power to compensate for overloading the hydraulic system will also be too great to enable the vehicle to remain at rest, with the automatic transmission engaged in the drive line unless the vehicle brakes are set,

In order to overcome the difiicultiesenumerated above, it is one of the objects of the present invention to provide an hydraulic compensating means, whereby the idling speed ofthe engine connected with a pump for supplying hydraulic fluid to load devices, such as power steering mechanisms, and other such vehicle accessories, will be automatically increased during such time as an excessive overload exists in the hydraulic supply system to prevent stalling of the engine. 7

It is a further object of the invention to provide a hydraulic compensating mechanism for internal combustion engines which is capable of being quickly and easily modified for use with a variety of engines having varying operating characteristics and driving, and associated with hydraulic systems having varying operating pressure.

Other objects and advantages will be apparent to those skilled in the art after reading the attached specification in connection with the accompanying drawings, in which:

FIG. 1 is a schematic view of the hydraulic circuit of a conventional automobile illustrating the operation of a preferred form of hydraulic pressure compensating means constructed in accordance with the present invention; and

FIG. 2 is a cross-sectional view on an enlarged scale of the compensating means shown in FIG. 1.

Referring now to the drawing in detail, the compensating means is indicated generally by the numeral 10 in FIG. 1, and is arranged to operate in cooperation with the carburetor, indicated generally by the numeral 11,

of an internal combustion engine (not shown). As will be explained later, the compensating means is effective, upon the opening of a valve means, indicated generally by the numeral 12, for the purpose of operating a hydraulically operated device, or load, indicated generally by the numeral 13, the power for which means is supplied by a hydraulic pump, indicated generally by the numeral 14.

The load means 13 may be any one of numerous devices supplied on automobiles, trucks or buses of today, and operated by hydraulic fluid such as a servo-mechanism for assisting in steering the vehicle, a power-operated convertible top, Window lifters, etc. Naturally, the the valve means 12 may be a simple manual or electrically operated valve, or it may comprise a relatively complex double-acting valve such as is common in the case of hydraulic power steering mechanisms.

However, before describing the operation of the system in detail, the internal construction of the compensator will first be described.

In FIG. 2, a detailed cross-sectional view of the compensating device 10 is shown as comprising an elongated casing 15 having a longitudinally extending bore 16 at one end; and having an aligned counterbore 17 of larger diameter at the other end, in communication with the bore 16. The bore 16 may have its inner end slightly flai'red, as at 18, to facilitate the insertion of a piston 19 which, in turn, is provided with one or more annular grooves to receive the sealing rings 20. The piston is also provided with an elongated stem 21 and has a radially extending flange or stop 22 which limits movement of the piston in one direction by abutment with the base 23 of the counterbore 17.

The open end of the counterbore is threaded as at 24 to removably receive a closure plug 25 provided with a central opening 26 for slidably guiding the projecting end of the stem 21. The end of the stem is also threaded as at 27 to adjustably receive an internally threaded cap or button 28 and a lock nut 29.

The plug 25 is also counterbored to provide an e1ongated tubular shroud 30, the outer end of which provides an abutment or stop to limit movement of the piston by engagement with the flange 22 when moving in a direction opposite to that caused by abutment of the flange with the bottom ofthe counterbore 17.

The extent of movement of the piston toward the right, as viewed in FIG. 2, may be adjusted by the insertion of one or more spacers 31- between the head of the plug 25 and the end of the casing 15.

Biasing means, such as the helical spring 32, is provided to urge the piston towards the left, as viewed in FIG. 2. This spring surrounds the stem 21 and is received Within the counterbore of the plug, one end of the spring bearing against the base 33 of the counterbore, the other end of the spring being in engagement with one or more spacers 34 placed on the stem 21, these spacers, spacers, in turn, bearing against the flange 22. By the addition or removal of these spacers, the force exerted by the spring may be varied to suit the conditions of operation. It will also 'be evident that the spacers could be placed at the other end of the spring or, if necessary, spacers could be inserted at both ends of the spring.

The open end of the bore 16 is threaded, as at 35, to receive a conventional hydraulic fitting (not shown) for connection with the conduit 36 (see FIG. 1). The casing 15 is also provided with a threaded opening 37 which is in communication with the bore 16 by means of the aperture 38. A conventional bleeder valve 39 is received in the opening 37 so that air may be removed from the system after the hydraulic connections have been made. The casing 15 is also provided with a bracket 40 to enable To install the compensator, the casing should be attached to the engine in such a position that when the piston 19 is in its retracted position (as shown in FIG. 2) the cap 28 will just be in contact with an abutment 41 of the throttle control arm 42 of the carburetor when the throttle is in its idling position, care being taken, of course, to see that the compensator is position so that movement of the piston under the influence of excess pressure in the vbore 16 will cause the throttle to open slightly.

Conduit 36 may then be connected to the high pressure side of the gear pump 14 by removing the high pressure supply conduit 43 and substituting a T fitting 44. The high pressure conduit is then re-connected to the T whereby the conduit 36 and bore 16 will thereafter be under the influence of fluid under the same pressure as exists in the conduit 43.

In operation, whenever the gear pump 14 is called upon to supply fluid to actuate the load device 13 as a result of operation of the valve 12, if an excessive force must be applied to the load device, the pressure developed in conduit 43 will be communicated through conduit 36 to the piston 19. If the pressure is not abnormal, movement of the piston Will be resisted by the biasing means 32 and the idling speed of the engine will not be affected.

However, if the force required by the load is excessive, the pressure built up in the fluid system, including conduits 43 and 36 behind the piston 19, will exceed the resistive forces of the spring 32 and movement of the piston and its associated stem 21 toward the right in FIG. 2 will take place to a limited extent. This movement of the stern will cause a slight opening of the throttle of the carburetor 11 causing the engine to increase speed to prevent stalling. The extent of opening of the throttle will be in proportion to demand of the hydraulic system for abnormal power.

A particular advantage of the present invention is the fact that the device is capable of attachment to various makes and models of engines, without the necessity of producing a separate type of device for each engine. For example, the location of the casing 15 with respect to the throttle arm of the carburetor may be varied in view of the fact that the eflective length of the stem 21 can be changed by rotation of the cap 28.

Secondly, in order to prevent inadvertent racing of the engine, the movement of the piston, under excess hydraulic pressure, to open the throttle is limited by virtue of the stop or abutment of the flange 22 with the shroud '30 and the position at which this limiting action takes place can be varied by the addition or subtraction of spacers 31.

Finally, the resistive force of the spring 32 may be regulated by means of the addition or subtraction of spacers 34 so that the device may be adapted to hydraulic systems having varying operating pressures.

It will thus be evident that this invention provides an extremely flexible device capable of use as an attachment or replacement in a widely varying number of applications.

Having described and shown a preferred form of the invention, various modifications and improvements may be made in the construction of the invention which would come within the scope of the annexedv claims.

I claim:

1. In a compensating mechanism for use with hydraulically driven load devices supplied with fluid under pressure by a pumpdriven by an internal combustion engine having a carburetor throttle valve having an idling position and movable in one direction to increase engine power, the combination including, an elongated casing having a bore at one end and a piston slidable therein,

; means for placing said bore in communication with fluid supplied to a load device by a pump driven by an internal combustion engine to move said piston in one direction in response to fluid pressure increase, said casing having a second bore at the other end, said piston including a steam extending exteriorly of the casing through said second bore for connection with the throttle valve of an internal combustion engine to move said throttle valve to increase engine power in response to movement of the piston in said one direction, elongated plug means removably received axially within the second bore, stop means connected with said piston and arranged for abutting engagement with said plug means to limit movement of the piston, coil spring means connected between the plug means and the piston for yieldably resisting movement of 2 the piston, spacer means for adjustably axially position- References Cited by the Examiner UNITED STATES PATENTS 2,634,681 4/1953 Rowell 10316 2,690,712 10/1954 Foote 10316 2,918,040 12/1959 Lieser 9213 2,931,305 4/1960 Stratton 10316 FOREIGN PATENTS 545,445 7/ 1922 France.

LAURENCE V. EFNER, Primary Examiner. 

1. IN A COMPENSATING MECHANISM FOR USE WITH HYDRAULICALLY DRIVEN LOAD DEVICES SUPPLIED WITH FLUID UNDER PRESSURE BY A PUMP DRIVEN BY AN INTERNAL COMBUSTION ENGINE HAVING A CARBURETOR THROTTLE VALVE HAVING AN IDLING POSITION AND MOVABLE IN ONE DIRECTION TO INCREASE ENGINE POWER, THE COMBINATION INCLUDING, AN ELONGATED CASING HAVING A BORE AT ONE END AND A PISTON SLIDABLE THEREIN, MEANS FOR PLACING SAID BORE IN COMMUNICATION WITH FLUID SUPPLIED TO A LOAD DEVICE BY A PUMP DRIVEN BY AN INTERNAL COMBUSTION ENGINE TO MOVE SAID PISTON IN ONE DIRECTION IN RESPONSE TO FLUID PRESSURE INCREASE, SAID CASING HAVING A SECOND BORE AT THE OTHER END, SAID PISTON INCLUDING A STEAM EXTENDING EXTERIORLY OF THE CASING THROUGH SAID SECOND BORE FOR CONNECTION WITH THE THROTTLE VALVE OF AN INTERNAL COMBUSTION ENGINE TO MOVE SAID THROTTLE VALVE TO 